1. Field of the Invention
The present invention relates to a stabilizer bushing constituting a stabilizer of a vehicle, and to a bushing-equipped stabilizer bar using the same.
2. Description of the Related Art
A stabilizer has been provided in vehicles including automobiles to stabilize their postures for improvement in driving stability and controllability. The stabilizer stabilizes the posture of the vehicle by torsion reaction force of the stabilizer bar. The both edge parts of the stabilizer bar are attached to the left and right suspension arms on the side of the wheels, while the medium part of the stabilizer bar is attached on the side of the vehicle body via the stabilizer bushing. Under a great difference of displacement amount between the left and right suspension arms, the torsion reaction force of the stabilizer bar restrains the displacement of the left and right suspension arms. This reduces the vehicle roll and thus stabilizes the posture.
The stabilizer bushing that attaches the medium part of the stabilizer bar on the side of the vehicle body has a tubular main rubber elastic body. This stabilizer bushing connects the stabilizer bar and the vehicle body to one another using its elasticity, by being disposed about and attached to the stabilizer bar and by being attached on the side of the vehicle body via an outer bracket, which is superposed on its outer peripheral surface of the stabilizer bushing.
Although the stabilizer bushing can be disposed about the stabilizer bar without being bonded thereto, the inner peripheral surface of the main rubber elastic body may be bonded to the outer peripheral surface of the stabilizer bar to further improve the driving stability and the controllability and prevent entry of debris into the gap between the stabilizer bushing and the stabilizer bar. For example, Japanese Unexamined Patent Publication No. JP-A-2011-168102 discloses a structure wherein the inner peripheral surface of the main rubber elastic body is adhered to the outer peripheral surface of the stabilizer bar with an adhesive.
However, the stabilizer bar to which the stabilizer bushing is adhered may suffer from durability deterioration. Static stress due to the attachment of the stabilizer bushing to the vehicle body and the stabilizer bar and dynamic stress due to vibration input concentrate on the axial edge parts of the inner peripheral surface of the main rubber elastic body. This results in such a durability deterioration factor as great tensile strain, which may cause cracking in the main rubber elastic body.